Rice (Oryza sativa L.) grown in winter season in tropical and subtropical regions are influenced adversely by the climatic
conditions, which is characterized by overcast sky posing low sunshine hours during the vegetative to reproductive growth
stages of the crop. Rice plant requires about 1500 bright sunshine (BSS) hours for the period from transplanting to maturity.
Instead, prevalence of only about 800-900 BSS hours during August to December in places like Northeastern region of India
hampers the physiological efficiencies, and ultimately the productivity of winter rice crop (Bharali et al., 1994). It’s because,
solar radiation in tropics is one of the major climatic factors limiting grain yield in rice